the smooth serrations are pretty ideal for it. they kind of grab the rope more than a straight blade but don't get stuck. the knife also doesn't get stuck when you're plunging it through something. it's a great design and build, and i can see why it's been so popular in america for so long.

I've used a triangular stone to sharpen serrations before. It works, but its still more work than sharpening a regular edge. Also I like to finish my sharpening on a strop, which isn't really an option for serrations.

Try sharpening the blade on the non-serrated side only. Also, sharpen more often.